Interference Alignment via Precoding Matrix Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wireless communication systems with multiple transmission/reception nodes face challenges in controlling interference, particularly due to the difficulty in sharing channel state information (CSI) among nodes, which limits the implementation of interference alignment techniques.
Innovation Solution
A method where reception nodes share CSI via device-to-device (D2D) or ad-hoc networks to calculate and feed back precoding matrices to transmission nodes, enabling interference alignment without requiring all nodes to know channel information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If interference alignment technique is used to obtain channel capacity at high SNR, then channel capacity is maximized, but implementation becomes difficult because all reception nodes and transmission nodes must know channels between all nodes
Solution Approach 1:
The patent segments the channel information sharing requirement by having each reception node share channel information only with its paired reception node, rather than requiring all nodes to know all channels. This segmentation reduces the complexity from O(N^2) to O(N) while still enabling interference alignment through coordinated precoding between paired nodes.
Solution Approach 2:
The patent introduces a master reception node as an intermediary that collects channel information from multiple reception nodes and coordinates the precoding matrices. This intermediary approach allows distributed nodes to achieve centralized interference alignment benefits without direct all-to-all channel knowledge, reducing implementation complexity.
2Reliability
If dirty-paper coding technique is used to obtain channel capacity in multiuser MIMO environment, then channel capacity is obtained, but a significantly complex coding technique such as lattice code is required and transmission node must know CSI of all links
Solution Approach 1:
The patent replaces the complex and computationally expensive lattice code with simpler precoding matrices that can be easily calculated and updated. These simpler precoding solutions achieve similar interference cancellation benefits without the heavy computational burden of dirty-paper coding, making the system more practical for real-time implementation.
3Ease of operation
If one transmission node knows only its own transmission signal, then inter-cell interference control is simplified, but positive cooperation between cells becomes impossible
Solution Approach 1:
The patent implements feedback mechanisms where reception nodes measure interference from neighboring cells and report this information to their serving transmission nodes. Transmission nodes then use this feedback to adjust their precoding matrices, enabling cooperative interference control without requiring direct knowledge of other transmission nodes' signals. This feedback loop achieves coordination while maintaining operational simplicity.
Data Source
AI summary
Disclosed is method for controlling interference in a wireless system having multiple sending and receiving nodes. In the method for controlling interference in a wireless system having multiple sending and receiving nodes, a plurality of receiving nodes share each other's channel information, each of the receiving nodes uses the shared channel information to calculate a precoding matrix which is fed back to the sending nodes, and each of the sending nodes uses each of the precoding matrices received as feedback to transmit a send signal to the receiving nodes, thereby controlling interference. Complete interference alignment can be achieved even by just sharing channel information between receiving nodes, and the invention can be employed not only for inter-cell interference but also for intra-cell interference environments.